The present invention generally relates to tool-bit holders. Specifically, the present invention relates to a tool-bit holder that automatically captures tool-bits as they are inserted into the holder.
In many situations, an operator must frequently change tools while working on a particular project. Often the operator is in a position where quickly exchanging one tool-bit for another is awkward. In order to change tool-bits held within existing tool-bit holders, an operator must manipulate a tool-bit locking mechanism. For example, to change tools held by a conventional three-jaw chuck, the operator must loosen the jaws to remove or insert a tool-bit, and tighten the jaws to secure a tool-bit. This usually requires the operator to use both hands to perform an exchange. Because of the awkwardness inherent in exchanging tools in such tool-bit holders, the operator""s work is slowed.
In some situations an operator may not be able to access the securing or releasing mechanism of the tool-bit holder. For example, such mechanisms are inserted into a handle, such as a screw driver handle, such that to directly activate a sleeve or other mechanism for securing or releasing the tool-bit may be impossible. These situations require that a tool-bit be automatically secured or released by the tool-bit holder as the tool-bit is inserted or pulled out of the tool-bit holder.
Several devices have been designed to reduce the awkwardness inherent in exchanging tools in a tool-bit holder. However, all require some degree of manipulation of the tool-bit holder to secure and release a tool-bit shank. As a result, an automatic tool-bit holder in which a tool-bit shank may be inserted and secured without additional manipulation of a locking or releasing device would be highly desirable.
The invention is a tool-bit holder for a tool-bit that automatically captures a shank of the tool-bit as the shank is inserted into the holder and prevents axial retraction of the tool-bit while the holder is in a locking position.
The automatic tool-bit holder of the present invention includes a hub having a longitudinal bore for inserting and capturing the shank. The hub includes a radial bore through which a detent ball may intrude into the longitudinal bore and seat into a circumferential groove in the shank of the tool-bit. The radial bore has a width smaller than the diameter of the detent ball to prevent the detent ball from falling radially into the longitudinal bore of the hub.
A spring or the like, axially biases a sleeve to force the detent ball in contact with an inner ramp face. Preferably, sleeve lies at least partially within a fixed collar disposed annularly about the hub. As the detent ball is forced into contact with the inner ramp face, the detent ball is directed radially inwardly along the inner ramp face and through the radial bore into the hub to contact the shank, and ultimately to seat in the groove to capture the tool-bit. The tool-bit is released when the bias force is relieved or countered, by axially sliding the sleeve relative to the hub.
In one alternative embodiment of the present invention, the sleeve is slidable within the longitudinal bore, eliminating the need for a fixed collar. The sleeve has an opening axially aligned with the radial bore to carry the detent ball. A compressed spring disposed between the sleeve and a closed end of the longitudinal bore provides the axial bias force pressing the detent ball in contact with an inner ramp face of the radial bore. As the detent ball is forced into contact with the inner ramp face, the detent ball is directed radially inwardly along the inner ramp face and through the opening in the sleeve to contact the shank, and ultimately to seat in the groove to capture the tool-bit. The tool-bit is released when the bias force is relieved or countered, by axially sliding the sleeve relative to the hub.
The present invention may also be defined in relation to a tool-bit holder of the type which has a hub a detent ball, a sleeve and a spring. The hub has a longitudinal bore formed for axially receiving a tool-bit shank therein, such that the longitudinal bore has an open end and a terminating face. The hub also has a radial bore therethrough. The detent ball is radially movably disposed in the radial bore of the hub for selected engagement with a circumferential groove on the tool-bit shank. The sleeve is axially slidably mounted relative to the hub or engaging the detent ball and the spring biases the sleeve into engagement with the detent ball. The present invention includes a radial bore in the sleeve that communicates with the radial bore of the hub for receiving the detent ball. In addition, the invention includes a longitudinally extending inner ramp face that is fixed relative to the hub for engaging the detent ball. The inner ramp face is opposed to the bias of the spring such that the inner ramp face extends radially outwardly toward the terminating face of the longitudinal bore.